Geoengineering, a roll of the climate dice

Published Tuesday, September 18, 2012 in the New Brunswick Telegraph Journal.

Geoengineering is the process of using man-made interventions to deliberately manipulate our global climate. Far from being a theory pulled from science fiction, it is actually an area of much research, discussion and debate. Here’s a short overview.

The background
Our planet’s atmosphere is like a thin, one-way blanket. It allows sunlight to enter and reach the surface of Earth, where it turns to heat. Most of that heat is radiated right back up into space, but our atmospheric blanket keeps in just the right amount to keep our planet at a perfect temperature for life.

But that delicate balance is changing. By burning oil, coal and natural gas, humans are dumping 90 million tonnes of carbon dioxide into the air every day, and that is making our thin atmospheric blanket keep in more heat than before – so the planet is warming.

Earth’s temperature is expected to rise to dangerous levels unless global emissions are cut soon, but breaking our global addiction to fossil fuels is an enormous challenge. So if we can’t prevent climate change, scientists and engineers are trying to assess whether there are things we can do to somehow reverse or offset it. In a nutshell, that’s geoengineering.

Two strategies
So how does one go about modifying a planet’s climate? There are two main strategies under consideration.

The first is to reduce the amount of sunlight reaching Earth’s surface. In the past, big volcanoes like Mount Pinatubo and Mount St. Helens have caused temporary global cooling because they emitted large amounts of sulphur high into the atmosphere, and that sulphur acted as a shade, keeping out sunlight. So the thinking is that if we mimic volcanoes and shoot sulphur particles into the upper atmosphere, we should be able to offset the warming caused by the greenhouse gases we’ve produced.

Other proposed ways to reduce sunlight include placing huge numbers of small mirrors in space above Earth; whitening clouds to make them more reflective; and setting up huge reflectors in deserts.

The second main strategy is to devise ways to absorb carbon dioxide out of the atmosphere, restoring our thin blanket so it goes back to keeping in just the right amount of heat. The leading proposal would have us sprinkle massive amounts of iron into our oceans to enhance the growth of algae. The algae would absorb CO2 from the air, then die and sink to the bottom, taking the carbon with it.

The risks
Perhaps you found yourself getting a bit uneasy while reading the above paragraphs. A fair reaction; geoengineering is rife with uncertainty.

For example, how can we be sure any technique eventually chosen will work, or that we can control it once started? (The short answer is, we won’t know until we try – and given that the sole laboratory for experimentation happens to be the planet we live on, it’s a risky roll of the dice.)

Or – how can we know there will not be unexpected side effects like acid rain or changes in rainfall patterns?

Or – how would diminished sunlight affect the growth of the crops we depend upon?

Or – how would global geoengineering be administered? Who would determine how much, and who would pay? What would it take to get global agreement? What if some nation decided to go it alone?

Et cetera. And geoengineering doesn’t address the root of the problem, global greenhouse gas emissions. Unless we reduce emissions, there will be a constant need for ever more geoengineering to offset ever more warming.

‘A bad idea whose time has come’ is how some pundits have described geoengineering. The fact it is even being considered speaks to the depth of our climate crisis.

The last word
In 2009, the respected Royal Society in London conducted an extensive study on geoengineering. It concluded, “The safest and most predictable method of moderating climate change is to take early and effective action to reduce emissions of greenhouse gases. No geoengineering method can provide an easy or readily acceptable alternative solution to the problem of climate change.”